Due to major structural changes in the 1980s, South Korea initiated an international contract labor program known as the industrial trainee system in 1991. Started ostensibly as a temporary measure to deal with domestic labor shortage in the declining manufacturing sector, the program has spread recently to other sectors, including fisheries, construction and agriculture. Currently, over 300,000 unskilled foreigners reside in South Korea, of which two out of every three persons are identified as unauthorized workers. This article examines how the South Korean industrial trainee program systematically produces unauthorized workers and highlights the role of non-governmental organizations (NGOs) in protecting the human rights of foreign workers. The successful collaboration of South Korea’s civil society stems from its unique historical formation, rooted in democracy movements of earlier decades. It also implicates strong prospects for substantive integration of foreign workers and, as a consequence, suggests important changes in the country’s social and economic structures.